。
She aspired to become an actress.
Literal
She [topic-は] actress [becoming-になる] [nominalizer-こと] [object-を] aspired-to.
志す (こころざす) is a literary verb meaning 'to aspire to' or 'to set one's heart on.' It carries more gravity and personal resolve than the more common 目指す (to aim for) — using 志す suggests deep commitment to a life path rather than just setting a goal. The こと nominalizer packages 女優になる (becoming an actress) into a noun phrase that serves as the object of 志した.